Electrical safety (household wiring): Select the correct material property required for a mains fuse wire. Fuse wire must melt quickly to break the circuit and must also offer suitable resistance to limit fault current. Choose the combination of material properties that a fuse metal should have.

Given data

• Context: Household electrical fuse wire requirements.
• Task: Identify the correct combination of material properties for a safe, effective fuse.

Concept/Approach
A fuse is a deliberate weak link that must melt first under excess current to open the circuit. Hence it should have a low melting point. To produce adequate heating even at modest overcurrents, its material should have relatively high resistivity so that P = I²R heating is significant in the fuse element.

Reasoning
• Low melting point → ensures quick melting during overcurrent. • High resistivity → more heat generated for a given current, assisting prompt operation. • Common alloys (e.g., tin–lead) reflect these desired properties.

Common pitfalls
Choosing high melting point (would delay blowing) or low resistivity (would reduce I²R heating), both undesirable for fuses.

Final Answer
Low melting point and high resistivity